/Engine/Source/Editor/MeshPaint/Public/IMeshPainter.h
Internal painting functionality, is called from Paint and PaintVR and implemented in the derived painters
bool PaintInternal ( const FVector & InCameraOrigin, const [TArrayView](API\Runtime\Core\Containers\TArrayView)< TPair< FVector, FVector >> & Rays, EMeshPaintAction PaintAction, float PaintStrength )